*Severe Weather Threat Wednesday.*
SW Louisiana Forecast Discussion...The advancing potent Pacific storm system is on the way! Today was a day of continued transition with a very moist and unseasonably warm air mass residing over the forecast area. Clouds were present throughout the day with a few peaks of sun. The fog wasn't as much of an issue as previously thought due to enough atmospheric mixing overnight. Southerly winds pumped in Gulf moisture out ahead of the advancing trough today, and high temperatures were near the 70 day threshold for the first time all year. A few showers dotted the landscape late this afternoon and early this evening, but for the most part it has been another dry day. It should be an uneventful night weather wise on this Tuesday night as we await the potential severe weather tomorrow. Overcast skies will continue as will the low-level Gulf flow. This will result in the continuation of rising dew points, and increasing humidity. Overnight lows should be well above the normal for mid January. Minimums should drop into the upper 50s along the I-10 corridor, and mid 50s North, while the coastline holds up into the low to mid 60s. A small rain chance is indicated for the overnight hours as the moisture increases across the area, but a cap in the upper levels of the atmosphere tonight should limit rainfall activity to no more than a sprinkle or very light shower. Fog possibilities will be another forecast concern for tonight. Certainly, dense fog will occur over the coastal waters and just inland along the coast, but some of this fog will make it inland especially along and South of I-10. At this time, it doesn't appear that it's going to be very dense with the cloud cover in place and enough mixing to keep the atmosphere stirred up. However, the deep moist air mass should allow for some fog formation especially due to the temperature differences between land and water.
Wednesday is when our attention turns to the first possible severe weather event of the new year. The vigorous Southern Stream Pacific storm system and associated upper level low and trough will be moving into the region. Many of the ingredients necessary to produce severe weather are in place, and other will conglomerate on Wednesday to warrant the severe potential. The day should start dry with just some clouds and fog. Any fog will be a distant memory by mid-morning, and we'll be watching how things begin to unfold from the severe weather aspect. The entire forecast area is highlighted for a slight risk of severe weather for the day 2 period (Wednesday) by the Storm Prediction Center in Norman, OK. Each severe weather set up is a different animal, and there is always a fine line. Seasonal environments have to be considered as well. That being said, here is what I see...the aforementioned upper level low will only slowly lift NE, and disturbances emanating out ahead of it will be moving across the area. The prolonged Southerly fetch of the last couple of days has brought a plentiful moisture return to the area. There will be sufficient instability in place with the possibility of low 60 dew points across the area. I believe the greatest amount of instability will be just to our East from parts of Acadiana over towards New Orleans.
Convection will likely be ongoing Wednesday morning across parts of Texas, rain and embedded thunderstorms is currently ongoing from near Dallas up into Oklahoma. This activity will advance and build to the SE through the night and on Wednesday morning as the trough approaches. The dynamics appear to be lacking over SE Texas, so that area should see not much more than just a few thunderstorms. The ingredients to produce the severe weather look like they will congeal right over SW Louisiana, and since it appears we'll be right on the line of where the greatest instability will be, that is why I believe the greatest threat will be over Acadiana. Rain and thunderstorms should begin to affect the region Wednesday afternoon, and continue through the evening hours. It won't rain constantly during that time, but there could very well be 2-3 different times that it rains. There really isn't the presence of a cold front associated with this system, so a classic MCS set up is not expected. However, with the upper level energy in place the environment may be more conducive to supercellular development. The upper level low will generate cold air aloft, which creates an unstable air mass. This often leads to a threat of large hail. The surface based winds will be out of the SE, while winds aloft out ahead of the ULL will be coming from the SW, and this will create shear (rotation) in the atmosphere, therefore the threat for a few tornadoes will be realized. The atmospheric profile suggests that damaging wind will be the greatest threat across the area. The amount of wind shear will be greater to our East, therefore, the aforementioned area will have a higher risk of tornadoes. The strong left-front quad (LFQ) of the Subtropical Jet Stream (STJ) will be positioned right over the area. This will make conditions favorable for damaging winds. The winds could be on the order of 70-80 mph in the strongest storms. Daytime heating will also add to the fray, as the primary threat hours for this event should be between 4p.m. and 10p.m. Certainly some scattered showers will occur before this time, but the main lobe of energy associated with this system will be crossing the area during that 6 hr. period. January is not a climatoligically favored month for severe weather, but often times in an El Nino pattern it can produce a significant severe weather event in January. Pinpointing exactly where there's going to be severe weather, and where there just be a general thunderstorm is near impossible. I would suspect that there will be multiple reports of severe weather across the state Wednesday through Wednesday night. A factor of inhibition will be the cloud cover as not much in the way of sunshine is expected. Sunshine would of course heat the atmosphere up even further, and would therefore increase instability. The severe weather threat will end overnight Wednesday as the Pacific trough moves through. Like I said, there's not really a cold front associated with this system, so while drier air will move in, it will remain warm. For Wednesday, highs should reach the low to mid 70s as the unseasonable warmth continues. Gusty winds are in the offing as well with the deepening pressures across the area. South winds over 25 mph at times are possible. Rain chances will be likely across the area, but not maxed out. The system is a quick mover thanks to the fast zonal flow across the area, so rainfall totals should be less than inch. Here is some graphical representation.
Beyond Wednesday, the forecast improves, but the active pattern continues as well. Showers and a few thunderstorms will be possible for a good portion of Wednesday night, but rapid clearing should occur as the trough lifts out and we remain in between Pacific systems. High pressure takes over for Thursday with skies becoming sunny. Temperatures will remain above normal with a morning low in the mid 50s, while highs make it feel so much like Spring. Highs should reach or exceed 75. The high pressure remains in control for Friday, and this should result in a beautiful end to the work week. A "coolish" start on Friday with a low in the mid 40s is looking about right at this time. Sunny skies and lower humidity values for Friday will result in a large diurnal range with highs reaching the upper 60s to lower 70s Acadiana. The active pattern in place means we'll experience fast changes, and that will certainly be the case again beginning late Friday. Friday will continue to be dry, no doubt, however a return flow of Gulf moisture will commence Friday night, and this will of course bring back the humidity. Friday night will remain clear, but temperatures will be back into the 50s. Fog could be an issue as well for this period, but later forecasts will determine such a possibility. The weekend starts dry on Saturday with just increasing clouds, humidity, and wind as yet another potent Pacific storm moves across the country embedded into the Southern Stream. Saturday maximums should once again reach the lower 70s as the warm and unstable air mass rolls on. It is too early to be specific about details this far in advance as far as dynamics are concerned, and I suggest we get past tomorrow's severe weather potential first. The bottom line is that, the next in the continuing parade of systems will cross the area likely overnight Saturday. It will bring with it a chance for showers and thunderstorms. A cold front will follow this system, and the end result will be a pattern shift to more typical January weather.
Conditions markedly improve on Sunday as a large area of high pressure builds in as the trough shifts East. A CAA regime should be firmly entrenched by Sunday afternoon, and you can expect a high in the mid 60s after a morning low in the upper 40s. Sunday evening looks great if you have any outdoor plans to get ready for the Saints game. Even cooler weather will trickle down into the forecast area through the end of the forecast period. We'll be back in coats and long sleeves by Sunday as the colder, more seasonable air moves in behind the latest in a series of Pacific troughs. The lows for Monday and Tuesday mornings will be back in the frosty category in the mid 30s, and will flirt with freezing especially across the Northern half of the forecast area in the typical colder spots. The air will be a combination of Pacific and Canadian air, and it will remain chilly during the afternoon with highs in the mid to upper 50s. The colder and drier weather at the first of next week, may result in a temporary break down of the persistent El Nino pattern that we've seen so far this winter. A dry forecast is expected for Sunday-Tuesday. Re-enforcing surges of cool air will filter down the spine of the Rockies next week, to keep it cool and dry. Towards the end of the week moderation should occur, and you guessed, another El Nino type storm system should be in the offing. Winter isn't over as there are many signs that point to another Arctic blast during the first week of February. It is way too early to tell how cold it will be. Don't put away your winter clothes yet! Stay tuned for more on the severe weather potential for Wednesday!
Preliminary Numbers & Zone Forecast:
LCH 59/71 55/75 46/70 20 80 60 0 0 0
LFT 58/72 57/74 45/70 20 80 70 0 0 0
BPT 62/73 54/76 47/71 30 80 60 0 0 0
AEX 58/74 50/72 42/67 20 80 70 0 0 0
POE 58/74 51/72 43/68 20 80 70 0 0 0
ARA 57/73 57/73 47/70 20 80 70 0 0 0
Tonight...Cloudy with a few showers possible. Dense Fog forming after midnight. Low 59. SE wind 10 mph. Chance of measurable precipitation 20%.
Wednesday...Fog and/or low clouds early, dissipating by mid-morning, otherwise Mostly Cloudy, Warm, & Windy with showers & thunderstorms likely. Some severe weather possible in the afternoon. High 71. SSE wind 15-20 mph and gusty. Chance of rain 80%.
Wednesday Night...Cloudy with showers & thunderstorms likely with locally heavy rainfall and severe weather possible in the evening. Rain ending with clearing skies overnight. Low 55. SSW wind 10-15 mph. Chance of rain 60%.
Thursday...Mostly Sunny. High 75. West wind 10 mph.
Thursday Night...Clear. Low 46. Light North wind.
Friday...Sunny. High 70. NE wind 10 mph becoming SE.
Drew's 7 Day Outlook for Lake Charles & Vicinity
Wednesday
1-20-10
Low: 59
High: 71
Precip: 80%
Wind: SSE 15-20
Thursday
1-21-10
Low: 55
High: 75
Precip: 0%
Wind: W 10-15
Friday
1-22-10
Low: 46
High: 71
Precip: 0%
Wind: NE/SE 10
Saturday
1-23-10
Low: 51
High: 74
Precip: 30% PM...70% Overnight
Wind: SSE 10-15
Sunday
1-24-10
Low: 47
High: 62
Precip: 0%
Wind: NNW 15-20
Monday
1-25-10
Low: 36
Hiigh: 54
Precip: 0%
Wind: N 10
Tuesday
1-26-10
Low: 34
High: 53
Precip: 0%
Wind: N 5-10
...Marine Forecast...
Tonight...South winds 10 to 15 knots. Seas 3 to 5 feet. Areas of dense fog after midnight.
Wednesday...South winds 10 to 15 knots. Seas 3 to 5 feet. Areas of dense fog in the morning. A chance of showers and thunderstorms.
Wednesday Night...Southwest winds 15 to 20 knots. Seas 3 to 4 feet subsiding to 2 to 4 feet after midnight. A chance of showers and thunderstorms.
Thursday...West winds 15 to 20 knots decreasing to 10 to 15 knots in the afternoon. Seas 1 to 3 feet subsiding to 1 to 2 feet in the afternoon.
Thursday Night...Northwest winds around 10 knots becoming 5 to 10 knots after midnight. Seas 1 to 2 feet.
Friday...Southeast winds 10 to 15 knots. Seas 2 to 4 feet.
Good night and God bless!
-DM-
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